Polyester film elements and subbing compositions therefor



Sept. 11, 1962 (3,5, s c ETAL 3,053,661

POLYESTER FILM ELEMENTS AND SUBBING COMPOSITIONS THEREFOR Filed Aug. 18,1958 GELATIN AND TERPOLYMER RIENTED CRYSMLLIZABLE POLYETI'IYLHIETERERlHflL/ITE GELAT/N AND SILVER HAL/DE GELATIN AND TERPOLYMERFORIENTED CRYSTALUZABLE POLYEWWLENE TEPEPHTHALATE Fj g 3 ELATIN ANDSILVER HAL/DE GELAT/N AND TERPOLYMER CRXSTALLIZABLE POLYETHYLENETEREPHTHALATE N AND TERPOLYMER n Fi 4 AND SILVER HAL/DE AND TERPOLYMEROWST/ILUZABLE POLYETM1NE TEREPHTHAUITE GELRTIN AND TERPOLYMER ELATIN ANDSILVER HAL/DE TIN AND CELLULOSE NITRATE AND TERPOLYM ER cmmuznau'POLYE77-IYLENE TEREPHTHALATE AND TERPOLYMER AND CEL LULOSE NITRATEClemensB. Slarck Carl E Smith RichardJHellmtmn INVENTORS' BY W EM UnitedStates Patent 3,053,661 POLYESTER FILM ELEMENTS AND SUBBING COMPOSITIONSTHEREFOR Clemens B. Starck, Carl F. Smith, and Richard J. Hellmann,Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, NY, acorporation of New Jersey Filed Aug. 18, 1958, Ser. No. 755,788 5Claims. (CI. 96-87) This invention relates to polyester sheeting havinga resinous coating on at least one surface thereof, and moreparticularly to a polyester fihn base wherein the said resinous coatingfunctions as an improved anchoring substratum or subbing layer betweenthe film base and the light-sensitive, water-permeable colloid layer oremulsion disposed thereon, preferably a gelatino-silver halide emulsionlayer.

It is known that high molecular weight linear poly-' esters can beformed into sheets having many desirable physical properties which makethem attractive for use as photographic film bases. This is particularlytrue for highly polymeric ethylene glycol-terephthalic acid polyesters.However, polyesters of this class are very hydrophobic, and in order tosecure adhesion to it of a normal type of hydrophilic gelatino-silverhalide emulsion layer, it is necessary to provide one or moreintermediate anchoring layers, so-called subbing or substratum layers.Such subbing compositions usually comprise a resinous material in asolvent combination which has at least some solvent or swelling actionon the film base but which action is insufiicient to distort the surfaceof the film base. While various compositions and combinations of layershave been proposed for this purpose, such as a terpolymer' of vinylidenechloride composition, none have proven entirely satisfactory in actualcommercial practice. For example, the use of synthetic polymer subbingcompositions usually requires a second subbing thereover of a gelatincomposition prior to the application of the lightsensitive emulsionlayer. But even with the double subbing technique, the finalphotographic film elements have shown some skidding and spontaneousstripping of the emulsion layer after processing and drying operations.This defect is a serious drawback where the element is intended for usein connection with graphic arts and cartographic processes wherein theexposed and processed negatives are subjected to scribing to producesharp lines in the printed images, for example, in aerial surveyingwherein latitude and longitude lines are produced by scribing such linesthrough the emulsion layerof the exposed and processed negative.Obviously, the emulsion in this kind of use must adhere tightly to thefilm base so that the scribed lines will have clean edges withoutpeeling even after prolonged storage of I the scribed negative. Goodanchorage of the emulsion layer to the film base is also required inprocesses for reducing or intensifying the negative image because of theharshness of the conventional reagents employed for these purposes.

- Wehave now found that a very effective subbing composition for eitherunstretched or oriented polyester sheeting and film base obtained bydispersing gelatin and certain resinous synthetic polymers in anon-aqueous" solvent mixture containing in addition to low boilingsolvents from 5-3 0% by weight of the subbing composition ofa phenoliccompound represented by the following general formula: 1 j g wherein Rrepresents a hydrogen atom or an alkyl group of from 1-4 carbon atoms,e.g., methyl, ethyl, propyl, isopropyl, butyl, etc. groups. Amounts ofthe phenolic compound less than 5% and more than 30%, we have found,show markedly less adhesive power and give impractical final elements.The subbing layer adheres firmly to the film base, and when overcoatedwith a lightsensitive emulsion, preferably a gelatino-silver halideemulsion layer, the film element thus obtained retains all of thedesirable physical properties of the polyester film base with none ofthe above-mentioned disadvantages of emulsion skidding and strippingwith related prior art photographic elements. While the preferredgelatin composition is indicated above as a gelatino-silver halideemulsion, it will be apparent that non-sensitive gelatin compositionslikewise will adhere firmly to the film base, for example, an aqueousgelatin-cellulose derivative such as cellulose nitrate can be coatedover the subbed film base followed by overcoating with thegelatino-silver halide emulsion. For non-curling purposes a simpleaqueous gelatin solution usually suffices for overcoating the subbedrear surface of the film base, but this may also contain other materialssuch as antistatic agents, fillers, dyes, etc.

It is, accordingly, an object of the invention to provide a novel anduseful composition that adheres strongly to polyester film base orsheets, and more particularly to oriented crystallizable polyester filmbase represented by polyethylene terephthalate. Another object is toprovide polyester sheeting wherein a layer of the above novelcomposition is coated directly on at least one side of the sheeting andwherein at least one of the coated sides is overcoated with a layer ofgelatin composition. Another object is to provide a high stabilityphotographic element comprising a polyester film base of the above kind,but preferably an oriented crystallized polyethylene terephthalate,wherein at least one of the coated surfaces is coated with alight-sensitive composition, more particularly with a gelatino-silverhalide emulsion layer. Other objects will become apparent hereinafter.

In accordance with the invention, our novel photographic elements areprepared by applying the novel subbing'composition of the inventiondirectly on polyester film base, and more particularly on orientedcrystallizable polyethylene terephthalate film base, on one or bothsides but preferably on both sides, drying the subbed film base and thenapplying at least one lightsensitive gelatin composition over at leastone of the subbed surfaces, followed by drying the element so formed.Preferably only one of the subbed surfaces is overcoated with alight-sensitive layer, and the other subbed surface is coated with anon-sensitive gelatin one of the double coated sides with thelight-sensitive" composition. In this case also, the element may beprovided with a gelatin coating on the reverse side that preventscurling, back reflection and static charge build-' The novel subbingcomposition of our invention that is coated directly on the polyesterfilm base consists essentially of from 0.251.0% by Weight of gelatin,0.56.0% by weight of a resinous terpolymer consisting of (1) a majorproportion by weight of a vinylidene halide such as vinyl chloride orvinylidene chloride, i.e., from 80-90%, (2) a minor proportion by weightof a vinyl carboxylate of a saturated fatty acid containing from 2-4-carbon atoms such as vinyl acetate, vinyl propionate or vinyl butyrate,or an alkyl acrylate such as those containing from 1-4 carbon atoms,e.g., methyl acrylate, ethyl acrylate, butyl acrylate, etc., i.e., fromabout 9-19%, and (3) a decidedly lesser amount by weight of anunsaturated acid or anhydride such as itaconic acid, maleic anhydride ormaleic acid, i.e., from about 0.5-3.0%, in a solvent combination of from530% by weight of at least one phenolic compound defined in abovegeneral formula I and the remainder of the composition to make a totalof 100% being an alkane dichloride containing from 1-3 carbon atoms suchas methylene chloride, ethylene chloride and the propylene chlorides.Where the higher proportions of the resinous terpolymer are employed,advantageously up to about 25%, i.e., from about 1-25%, of the alkanedichloride is replaced with methanol to improve solubility of thecomponents. The preferred novel subbing compositions are the o-cresoland ethylene chloride combinations. A convenient way to obtain gooddispersal of the gelatin is to first dissolve it in the phenoliccompound and then incorporate the resulting mixture into a mixture ofthe other components of the composition. Advantageously, there may alsobe incorporated a hardener for the gelatin varying in amount from atrace (0.001%) to not more than 0.03%, preferably in the form ofCI'C136H20.

Typical subbing compositions of the invention that are coated directlyon the polyester film base come within the ranges specified in thefollowing general formulation given in weight percent.

FORMULA A Ingredient: Weight percent of total Gelatin 0.25-1.00 Resinousterpolymer 0.50-6.00 Phenolic compound 5.030.0 Gelatin hardenertrace-0.03 Alkane dichloride 94.25-57.97 Methanol 00-50 As previouslymentioned, it may sometimes be desirable to apply a second subbing overthe above substratum. For this purpose, a mixed gelatin-cellulosenitrate may be used, for example, a composition that comes within thefollowing general formulation given in weight percent:

In the above formulation, the acid dispersing agent may be any of theusual acids used for dispering gelatin, e.g., acetic acid. It may varymoderately, but preferably about of the weight of the gelatin. Thecellulose nitrate preferably is a low viscosity type of nitrogen contentabout 11% and being 80-90% soluble in alcohol. The amount of cellulosenitrate is dependent on the amount of gelatin varying from about 17-46%of the weight of the gelatin to give a coated layer consistingessentially of from 68-86% by weight of gelatin and from 32-14% byweight of cellulose nitrate, and in some cases some gelatin hardenersuch as chromic chloride. The amount of water is determined on thegelatin content and is present in amount approximately from 2 to 3 timesthe weight of the gelatin. In place of the cellulose nitrate, there maybe substituted a resinous terpolymer such as mentioned previously forthe subbing composition which is coated directly on the polyster filmbase, e.g., a terpolymer of vinyl chloride, vinyl acetate and maleicanhydride, but in this the acetone is replaced by an alkane dichloride,e.g., ethylene chloride.

When the subbing layer or layers have dried, an ordinary gelatino-silverhalide emulsion is coated thereover and dried. To eliminate any tendencyto curl, the other subbed surface is overcoated with a gelatincomposition containing no silver halide, but which may contain, ifdesired, antistatic agents, filter dyes, antihalation agents, and thelike. The photographic elements produced as above described arecharacterized by firm adherence of the layers to one another and to thepolyester film base, and show excellent dimensional stability undertesting, use and storage conditions.

Suitable polyester sheet materials for practicing our invention may beprepared from high molecular polyesters prepared by condensing adihydric alcohol with a dibasic saturated fatty carboxylic acid orderivatives thereof. As dihydric alcohol there may be mentioned anyglycol wherein the hydroxyl groups are on the terminal carbon atoms andcontaining from 2-12 carbon atoms, e.g., ethylene glycol, propyleneglycol, trimethylene glycol, hexamethylene glycol, decamethylene glycol,dodecamethylene glycol, 1,4-cyclohexane dimethanol, etc.; as dibasicacids may be mentioned those containing from 2-16 carbon atoms, e.g.,adipic, sebacic, decanedioic acid, hexadecanedioic acid, phthalic acid,terephthalic acid and alkyl esters thereof. However, other suitabledihydric alcohols and dibasic acids for preparing suitable polyestersfrom which sheetings can be prepared are described in J. W. Wellman US.Patent No. 2,720,503, dated October 11, 1955.

Representative subbed polyester sheeting and photo graphic elementsprepared therewith are shown in cross section in the accompanyingdrawings illustrating the invention. Referring to the drawings, FIG. 1illustrates an oriented crystallizable polyester film base 10represented by polyethylene terephthalate having a mixedgelatin-resinous terpolymer undercoat layer 11 (coated with the cresolcomposition of Formula A). In the preferred form, layer 11 also containsa hardener for the gelatin, e.g., chromic chloride.

The element shown in FIG. 2 is the same as that shown in FIG. 1, exceptthat a gelatino-silver halide layer 12 is coated over the subbing layer11.

The element shown in FIG. 3 is a preferred element and is the same asthat shown in FIG. 2, except that the subbing layer 11 is also coated onthe back of the film base 10.

The element shown in FIG. 4 is the same as that of FIG. 3, except thatan additional layer 13 (Formula B) of gelatin containing no silverhalide is coated over the subbing layer 11 on the back surface of thefilm base 10. It is also preferred.

The element shown in FIG. 5 illustrates a double subbed element whereinthe film base is first subbed on both sides with the subbing layer 11and then with a second subbing layer 14 over each layer 11 comprising amixed gelatin-cellulose nitrate, followed by a gelatino-silver halidelayer over one of the subbed layers 14 and a gelatin layer 13 containingno silver halide over the other of the subbed layers 14. Layer 13 isintended primarily to prevent curling but may also contain suitableantistatic materials, filter dyes, antirefiection agents, and the like.

The manner of practicing our invention is further illustrated by thefollowing examples:

Example 1 Ingredient: Weight percent of total Gelatin 1.0 Resinousterpolymer 1.0

86% vinyl chloride 13% vinyl acetate 1% maleic anhydride o-Cresol 20.0Chromic chloride 0.015 Ethylene chloride, suflicient to make a totalAfter drying, one of the coated surfaces was overcoated with an ordinarygelatino-silver halide emulsion and the other coated surface wasovercoated with an aqueous gelatin solution containing no silver halide.On drying and curing, no curl was observed. The photographic elementthus obtained, on testing, showed that the emulsion adhesion wasexcellent before, during and after processing. No skidding or strippingof the emulsion occurred when samples of the element were exposed andprocessed. The negatives produced had good definition and were readilyscribed on the emulsion side to give clean lines, and the printsreproduced therefrom showed sharp, well-defined lines. No edge peelingwas observed on storing the negatives for several weeks at relativelylow humidity, and the prints made from the stored negatives matchedperfectly those prepared from the same negatives prior to storing.Accordingly, the photographic element produced as above described hasoutstanding .utility in the graphic arts and related fields.

Example 2 The procedure of Example 1 was repeated. However, a secondsubbing layer was applied over the subbed film base prior to coatingwith the gelatino-silver halide emulsion. The second subbing compositionconsisted of the following components given as percent by weight.

Methanol, suflicient to make a total of 100%.

The photographic element obtained had generally similar properties tothose set forth for the element produced according to Example 1.

Example 3 An oriented crystallizable polyethylene terephthalate filmbase was roller coated on one side wi the following subbing compositionwherein the components are given in percent by weight.

Ingredient: Weight percent of total Gelatin 0.5 Resinous terpolymer 1.0

83% vinylidene chloride 15% methyl acrylate 2% itaconic acid o-Oresol20.0 Chromic chloride 0.019 Ethylene chloride, sufiicient to make atotal After drying, the subbed surface was overcoated with a 6 secondsubbing composition consisting of the following components by weightpercent.

Ingredient: Weight percent of total Gelatin 1.25 5 Acetic acid 0.12s

Cellulose nitrate 0.30 Water 2.50. Chromic chloride 0.019 Acetone 70.0

10 Methanol, sufiicient to make a total of 100%.

An ordinary gelatino-silver halide emulsion was coated over the doublesubbed surface, while a plain aqueous gelatin solution, i.e., containingno light-sensitive'materials, was coated on the reverse side of the filmbase. Tests indicated that the photographic element produced hadexcellent adhesion of the emulsion to the film base and it was anexcellent material for graphic arts and related processes.

Example 4 This example illustrates a photographic element having a mattesurface, and wherein a relatively large amount of the resinousterpolymer is used in the primary coat ing or substratum of orientedcrystallizable polyethylene terephthalate. In this case, some methanolis employed to improve the solvent power of the solvents, up to about56% for the primary subbing composition containing no water, and up toabout 25% for the second subbing composition to compensate for the waterpresent. The primary subbing composition by weight percent is asfollows.

Ingredient: Weight percent of total Gelatin 1.0 Resinous terpolymer 6.0

86% vinyl chloride 13% vinyl acetate 1% maleic anhydride 7 o-Cresol 20.040 Titanium dio 1.0 Ground glass (200 mesh) 0.5 Methanol 4.0 Ethylenechloride, sufficient to make a total 5 The subbed film base was dried,after which a second subbing layer was applied over the primary subbedsurface of a composition as follows: Ingredient: Weight percent of totalGelatin 1.0 Acetic acid 0.1 Resinous terpol-ymer 0.5

86% vinyl chloride 13% vinyl acetate 1% maleic anhydride Water 2.0Methanol 20.0

Ethylene chloride, sufficient to make a total of 100% An ordinarygelatino-si-lver halide emulsion was then applied over the double-subbedsurface of the film base, and the resulting element showed excellentadhesion of the emulsion to the film base before, during and afterprocessing. The storing tests also showed good dimensional stabilitywith no edge lifting or emulsion skidding under test conditions whichfollowed the processes generally employed in the graphic arts andcartographic practices.

The invention has been described in detail with particular reference tothe preferred embodiments thereof,

but it will be understood that variations and modifications can beeffected within the spirit and scope of the invention as describedhereinabove and as defined in the appended claims.

What we claim is:

l. A photographic element comprising a film base of an orientedcrystallizable polyethylene terephthalate having on at least one surfacethereof a substratum layer consisting essentially of a mixture in theproportions of (1) from 0.25 to 1.0 part by Weight of gelatin, (2) from0.5 to 6.0 parts by weight of a resinous terpolymer consisting of (a)from 80 to 90 percent by weight of units selected from the groupconsisting of vinyl chloride units and vinylidene chloride units, (17)from 9 to 19 percent by weight of units selected from the groupconsisting of units of a vinyl ester of a saturated fatty acidcontaining from 2 to 4 carbon atoms and units of an alkyl acrylatewherein the alkyl group contains from 1 to 4 carbon atoms, and (c) from0.5 to 3.0 percent by weight of units selected from the group consistingof maleic anhydride units, itaconic acid units and maleic acid units,and (3) from to 30 parts by weight of a phenolic compound having thegeneral formula:

wherein R represents a member selected from the group consisting of ahydrogen atom and an alkyl group of from 1 to 4 carbon atoms, and havinga gelatinosilver halide emulsion layer coated over at least one of saidsubstratum layers.

2. A photographic element comprising a film base of an orientedcrystallizable polyethylene terephthalate having on one surface thereofa substratum layer consisting essentially of a mixture in theproportions of (1) from 0.5 to 1.0 part by weight of gelatin, (2) from0.5 to 6.0 parts by weight of a resinous terpolymer consisting of (a)from 80 to 90 percent by weight of vinyl chlo ride units, (b) from 9 to19 percent by weight of vinyl acetate units, and (c) from 0.5 to 3.0percent by weight of maleic anhydride units, and (3) from 5 to 30 partsby weight of o-cresol, and having a gelatino-silver halide emulsionlayer coated over said substratum layer.

3. A photographic element comprising a film base of an orientedcrystallizable polyethylene terephthalate having on one surface thereofa substratum layer consisting essentially of a mixture in theproportions of (1) from 0.5 to 1.0 part by weight of gelatin, (2) from0.5 to 6.0 parts by weight of a resinous terpolymer consisting of (a)from to percent by weight of vinylidene chloride units, (b) from 9 to 19percent by weight of methyl acrylate units, and (c) from 0.5 to 3.0percent by weight of itaconic acid units, and (3) from 5 to 30 parts byweight of o-cresol, and having a gelatino-silver halide emulsion layercoated over said substratum layer.

4. A photographic element comprising a film base of an orientedcrystallizable polyethylene terephthalate having on both surfacesthereof a substratum layer consisting essentially of a mixture in theproportions of (1) from 0.5 to 1.0 part by weight of gelatin, (2) from0.5 to 6.0 parts by weight of a resinous terpolymer consisting of (a)from 80 to 90 percent by weight of vinyl chloride units, (b) from 9 to19 percent by weight of vinyl acetate units, and (c) from 0.5 to 3.0percent by weight of maleic anhydride units, and (3) from 5 to 30 partsby weight of o-cresol, and having a gelatino-silver halide emulsionlayer coated over at least one of said substratum layers.

5. A photographic element comprising a film base of an orientedcrystallizable polyethylene terephthalate having on both surfacesthereof a substratum layer consisting essentially of a mixture in theproportions of (1) from 0.5 to 1.0 part by weight of gelatin, (2) from0.5 to 6.0 parts by weight of a resinous terpolymer consisting of (a)from 80 to 90 percent by weight of vinylidene chloride units, (b) from 9to 19 percent by weight of methyl acrylate units, and (c) from 0.5 to3.0 percent by Weight of itaconic acid units, and (3) from 5 to 30 partsby weight of o-cresol, and having a gelatino-silver halide emulsionlayer coated over at least one of said substratum layers.

References Cited in the file of this patent UNITED STATES PATENTS2,341,877 Middleton et al. Feb. 15, 1944 2,548,520 Damschroder et al.Apr. 10, 1951 2,570,478 Pitzl Oct. 9, 1951 2,698,235 Swindells Dec. 28,1954 2,709,689 Damschrodel' et al. May 31, 1955 2,709,689 Herzog et al.May 31, 1955 2,794,742 Fowler et al. June 4, 1957 2,852,378 Nadeau et a1Sept. 16, 1958 2,853,457 Gates et al. Sept. 23, 1958 2,912,413 Baer Nov.10, 1959 2,943,937 Nadeau et al. July 5, 1960

1. APHOTOGRAPHIC ELEMENT COMPRISING A FILM BASE OF AN ORIENTEDCRYSTALLIZABLE POLYETHYLENE TEREPHTHALATE HAVING ON AT LEAST ONE SURFACETHEREOF A SUBSTRATUM LAYER CONSISTING ESSENTIALLY OF A MIXTURE IN THEPROPORTIONS OF (1) FROM 0.25 TO 1.0 PART BY WEIGHT OF GELATIN, (2) FROM0.5 TO 6.0 PARTS BY WEIGHT OF RESINOUS TERPOLYMER CONSISTING OF (A) FROM80 TO 90 PERCENT BY WEIGHT OF UNITS SELECTED FROM THE GROUP CONSISTINGOF VINYL CHLORIDE UNITS AND VINYLIDENE CHLORIDE UNITS, (B) FROM 9 TO 19PERCENT BY WEIGHT OF UNITS SELECTED FROM THE GROUP CONSISTING OF UNITSOF A VINYL ESTER OF A SATURATED FATTY ACID CONTAINIG FROM 2 TO 4 CARBONATOMS AND UNITS OF AN ALKY ACRYLATE WHEREIN THE ALKYKL GROUP CONTAINSFROM 1 TO 4 CARBON ATOMS, AND (C) FROM 0.5 TO 3.0 PERCENT BY WEIGHT OFUNITS SELECTED FROM THE GROUP CONSISTING OF MALEIC ANHYDRIDE UNITS,ITACONIC ACID UNITS AND MAELIC ACID UNITS, AND (3) FROM 5 TO 30 PARTS BYWEIGHT OF A PHENOLIC COMPOUND HAVING THE GENERAL FORMULA: